Andersen wanted to know if Portlands flourishing bicycle culture was making a dent in the number of travelers coming here who dont rent cars.

He discovered, by checking with Multnomah County records, that hotel and motel tax receipts by the county are up 26 percent since 2001 while car rental revenues are down 13 percent, after adjusting for inflation.

A multitude of factors could help explain the trend  such as more visitors driving here who dont need to rent cars. But Andersens research suggests that the Portland area's efforts to improve transit, walkability and bike-friendliness may be causing some visitors to ditch their cars.

"You can come and get around on the MAX, or your hotel might have a free bike that you can use," Travel Oregon spokeswoman Megan Conway told Andersen. "That's definitely appealing to the people who come here."